This invention relates to an audio-visual system and, more particularly, to an improved magnetic tape drive and transducer system for use with a multipurpose film handling cassette.
Multipurpose motion picture cassettes from which the film need not be removed during exposure, processing and projection operations are described in prior U.S. Pat. Nos. 3,615,127 of Edwin H. Land, issued Oct. 26, 1971; 3,600,071, issued to Rogers B. Downey on Aug. 17, 1971; and 3,895,862, issued to Joseph A. Stella, et al., on July 22, 1975. In the systems of the above-identified patents, a cassette is operated in a camera for exposure of the film strip and then subsequently loaded into a projector apparatus which first subjects the cassette to a sequence of operations which process the film strip to a viewable condition and then subsequently projects the developed recorded images for viewing thereof.
A variety of arrangements have been proposed whereby audio operations may also be included in such a motion picture cassette system. Exemplary of such audio-visual systems is that described in prior U.S. Pat. No. 3,604,790 of Edwin H. Land, et al., issued Sept. 14, 1971, and U.S. Pat. No. 3,856,387 of William R. Wray, et al., issued Dec. 24, 1974, and copending U.S. patent application Ser. Nos. 869,131 and 899,782. The above-cited patents describe a film handling cassette in which the film is permanently retained during sound recording and playback as well as exposure, processing and projection operations. In the systems of the above-cited issued patents, a magnetic sound recording track is included along one or both of the longitudinal borders of the film strip. While these systems provide generally acceptable audio reproduction, the inherent restriction of the narrow width of the audio track, which cannot be allowed to interfere with the image bearing portion of the film strip lying therebetween, limits the level of sound quality which may be achieved or, conversely, substantially increases the sophistication and the cost of the sound apparatus necessary for high fidelity stereo. One suggested arrangement for alleviating the above-noted problem is to provide a transparent sound track over the full width of the photographic film strip; however, this solution creates its own difficulties in that the sound layer must not only be exceedingly thin in order to provide adequate transparency, but also complicates film production because of the necessity of imposing this layer on the image area of the photographic emulsion surface.
The above-cited U.S. patent application Ser. No. 869,131 proposes a somewhat different solution to the problem by providing a separate audio magnetic tape which is interwound on the common supply spool with the photographic film strip. The magnetic tape and the film strip are simultaneously removed from the spool and advanced synchronously along separate paths such that the photographic and audio operational functions may be performed upon the strips as they progress along their different paths.
In a preferred embodiment, the multipurpose film cassette is received in an open-ended well in the projector apparatus and an audio accessory is provided for overlying the cassette well following insertion of a cassette therein. The sound tape passes from the upper end of the cassette, and the open upper end of the well facilitates engagement of the tape by the audio components of the audio accessory which is positioned above the well.
The above-cited copending U.S. application Ser. No. 899,782 provides a tape drive and transducer arrangement for use with such an accessory wherein the magnetic transducer head is disposed within a rotating, vacuum capstan in fixed relation to the centrally located portion of the sound tape. The sound tape in turn is held against the capstan and the stationary head by air pressure resulting from a partial vacuum which is internal to the capstan and presented to the tape by peripheral openings which overlie the tape margins.
Viewing or projection apparatus such as that with which the audio accessories of the type described hereinabove are adapted to be used are provided with various electrical motors and drive systems for implementing the several operating cycles upon the film cassette and, as a result, considerable vibration is present during operation of the viewer as a result of the various drive motors, drive trains, cooling fans and other mechanical components contained therein. Such vibrations transmitted to the top-mounted audio accessories may result in undesirable effects upon the quality of the stereophonic sound information reproduced by the sound accessory and accordingly, such vibration is undesirable. A further requirement of such top-mounted sound accessories is that certain of the audio components contained therein be precisely positioned with respect to the audio tape of the audio-visual cassette to assure proper registration therebetween and proper synchronization between the audio and video information.